Unlocking iPhone 4 on Baseband 04.12.01

[kingarabian]

Is it possible to unlock an At&t iPhone on BB 04.12.01? I want to use it with T-Mobile but all the guides online say it's not possible anymore. Is it possible to downgrade to a lower Baseband?

Rememeber not jailbreak, unlock.

Thanks guys!

[YoHoJo]

Made similar thread/researched I think the answer is no.
BUT there is some physical device you can buy, put into sim card slot, and it unlocks for you, supposedly any baseband.

Search my threads you'll find it in there.

[Markus]

BUT there is some physical device you can buy, put into sim card slot, and it unlocks for you, supposedly any baseband.

IIRC those Turbo SIM things only worked for the first few iphone 2g

[Brandon]

There's a couple technicalities where you can unlock this baseband without a piggyback sim or gevey sim.

http://maypalo.com/2012/06/05/unlock-iphone-4-baseband-4-11-084-12-01-on-ios-5-1-1-using-activation-tickets-with-redsnow-guide/

[Jim]

There's a couple technicalities where you can unlock this baseband without a piggyback sim or gevey sim.

http://maypalo.com/2012/06/05/unlock-iphone-4-baseband-4-11-084-12-01-on-ios-5-1-1-using-activation-tickets-with-redsnow-guide/

That's only for iPhones that were already unlocked to keep the unlock after updating software.